The first study conducted in a natural environment has shown that systemic pesticides damage bees' ability to navigate. Common crop pesticides have been shown for the first time to seriously harm bees by damaging their renowned ability to navigate home. The new research strongly links the pesticides to the serious decline in honey bee numbers in the US and UK — a drop of around 50 per cent in the last 25 years. The losses pose a threat to food supplies as bees pollinate a third of the food we eat such as tomatoes, beans, apples and strawberries.

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Scientists found that bees consuming one pesticide suffered an 85 per cent loss in the number of queens their nests produced, while another study showed a doubling in "disappeared" bees — those that failed to return from food foraging trips. The significance of the new work, published Science, is that it is the first carried out in realistic, open-air conditions.

"People had found pretty trivial effects in lab and greenhouse experiments, but we have shown they can translate into really big effects in the field. This has transformed our understanding," said Prof David Goulson, at the University of Stirling and leader of one of the research teams. "If it's only one meter from where they forage in a lab to their nest, even an unwell bee can manage that."